1. Field of the Invention
The present invention relates to an imaging apparatus, a data processing method, and a program, and particularly to an imaging apparatus, a data processing method, and a program for recording an image captured with the imaging apparatus records along with orientation information representing the direction in which the image was captured.
2. Description of the Related Art
In recent years, there has been a camera that includes an orientation sensor for detecting the direction in which the camera is oriented and, when capturing an image, acquires orientation information representing the imaging direction acquired with the orientation sensor. A camera of this type records the captured image along with the orientation information as attribute information (meta information) associated with the captured image on a medium (storage means).
Orientation information recorded on a medium as attribute information associated with an image is used, for example, to indicate the imaging direction on a map displayed on a display section of a PC or any other apparatus. Alternatively, when a panoramic image is produced by combining a plurality of continuously captured images, orientation information is used to determine the direction in which each of the images was captured. Orientation information is used in a variety of other applications.
An imaging apparatus that acquires and records orientation information is described, for example, in JP-A-2005-110031 and JP-A-2005-26859.
In a digital camera or other similar cameras, however, the timing at which an image is captured is not identical to the timing at which the captured image is recorded on a medium. The time difference is caused by the fact that after an image is captured, it takes time to record the captured image. For example, after an image is captured, a data processor in the camera encodes the captured image, formats a recording medium, performs other processes, and then records the captured image on the medium. A digital camera thus typically requires a certain processing period after imaging and before recording.
In many cases, a camera of related art, when recording a captured image on a medium, acquires the latest orientation information from an orientation sensor equipped in the camera and records the orientation information as the information on the imaging direction. Any change in the direction in which the camera is oriented during the period from the timing at which an image is captured to the timing at which the image is recorded on the medium causes the recorded orientation information to differ from the direction in which the image was actually captured.
A specific example will be described with reference to FIGS. 1 and 2.
FIG. 1 describes an image capturing and recording sequence in a typical single or continuous image capturing process.
FIG. 2 describes the sequence of capturing a plurality of images while moving a camera, processing the captured images in the camera to produce a horizontally elongated panoramic image, and recording the panoramic image.
An image capturing and recording sequence in a typical single or continuous image capturing process will first be described with reference to FIG. 1. FIG. 1 shows the sequence of
(a) imaging,
(b) recording, and
(c) acquiring orientation information. Time (t) elapses from left to right.
A user first captures an image 1 at time t1. The user then captures an image 2 at time t2, subsequently captures images afterward, and captures an image N at time t3. It is assumed that a total of N images are captured. The user captures images while changing the direction in which the camera is oriented.
Each of the captured images is encoded by a signal processor in the camera into a JPEG image or any other suitable compressed image. The encoded images, before recorded, are further converted into data compliant with a specified image recording format, such as the EXIF format. After these processes, the data are recorded on a flash memory or any other suitable recording medium.
As described above, the encoding and other signal processing typically require predetermined periods. The image 1, the image 2, and the image N are therefore recorded on the medium at time t4, t5, and t6, respectively, as shown in FIG. 1.
A sensor that acquires orientation information provides a controller (CPU) with information acquired with the sensor at pre-specified sampling time intervals. The controller acquires the latest orientation information acquired when a captured image is recorded on the medium and records the acquired orientation information on the medium.
As a result, the orientation information recorded in attribute information (meta information) associated with the image 1 is orientation information inputted from the orientation sensor immediately before the time t4, at which the image 1 is recorded. As a result, wrong orientation information of [135°] is recorded as the information representing the direction in which the image 1 was captured, as shown in FIG. 1. The recorded orientation information obviously differs from the orientation information of [0°] at the time when the image 1 was actually captured (t1).
Similarly, for the image 2 captured at the time t2, orientation information of [180°] acquired immediately before the image 2 is recoded at the time t4 is recorded, but the recorded orientation information differs from the orientation information of [45°] at the time of actual imaging action (t2).
As described above, the time lag between the imaging timing and the recording timing causes orientation information different from the orientation information at the time of the actual imaging action to be recorded as attribute information (meta information) associated with the captured image.
FIG. 2 describes the sequence of capturing a plurality of images while moving a camera, processing the captured images in the camera to produce a horizontally elongated panoramic image, and recording the panoramic image. FIG. 2 shows the sequence of
(a) imaging,
(b) recording, and
(c) acquiring orientation information, as in FIG. 1. Time (t) elapses from left to right.
The user sets the camera into a panoramic imaging mode and captures a plurality of images while moving the camera. After the images are captured, a data processor in the camera connects the plurality of images to produce a panoramic image and records the panoramic image on a recording medium.
In FIG. 2, time to represents the central time of the period during which the plurality of images that form the panoramic image are captured. After the user captures the plurality of images, the camera combines the images to produce a panoramic image, encodes the panoramic image into a JPEG image or any other suitable compressed image, and before recording the encoded image, converts it into data compliant with a specified image recording format. After these processes, the data are recorded on a flash memory or any other suitable recording medium.
The data processing described above typically requires a predetermined period, and the panoramic image is recorded on the medium at time tb, as shown in FIG. 2. In this case as well, the controller in the camera acquires the latest orientation information acquired when one of the captured images is recorded on the medium and records the acquired orientation information on the medium.
As a result, the orientation information recorded in meta information associated with the panoramic image 1 is orientation information inputted from the orientation sensor immediately before the time tb, at which the panoramic image 1 is recorded. As a result, wrong orientation information of [180°] is recorded as the information representing the direction in which the panoramic image 1 was captured, as shown in FIG. 2. The recorded orientation information obviously differs from the orientation information of [45°] at the time when the panoramic image 1 was actually captured (ta).
As described above, the time lag between the imaging timing and the recording timing causes orientation information different from the orientation information at the time of the actual imaging action to be recorded as attribute information (meta information) associated with the captured images.
On the other hand, an orientation sensor equipped in a camera is in many cases configured to acquire orientation information by using a combination of a magnetic sensor that detects earth magnetism and an acceleration sensor. The magnetic sensor, however, outputs a wrong detected value in some cases due to magnetism produced by a drive mechanism and an electronic member in the camera, that is, disturbance.
Specifically, the magnetic sensor may output a wrong detected value due to magnetism produced, for example, when a lens is driven at the time of focus adjustment or any other process during imaging operation.
An imaging apparatus of the state of the art, that is, an imaging apparatus that acquires orientation information, relates the orientation information to a corresponding image, and records them therefore has the following problems.
(a) Decrease in precision in orientation information due to the discrepancy between the time at which an image to be recorded on a medium is captured and the time at which orientation information is acquired
(b) Decrease in precision in orientation information due to disturbance